If there is one member of cabinet who understands the ins and outs of metadata, it’s Communications Minister Malcolm Turnbull.

Yet Turnbull has so far been nowhere to be heard as the government tries to explain its plan to force telecommunication companies and internet providers to retain the data for two years.

Turnbull is known to have been angry to have read about the cabinet national security committee’s metadata decision in the media. The powers-that-be in the Prime Minister’s office are known to be usually reluctant to deploy Turnbull.

But still, if the message is to be got out, he should be at the forefront in explaining what the government is on about. On Wednesday Tony Abbott created some confusion, and Attorney-General George Brandis when he appeared on Sky was trying so hard to avoid saying the obvious that he did little to clarify.

The plan is that telcos and internet service providers would be asked to keep data for two years, so potential evidence did not disappear into the commercial dustbin. “We’re not asking for new information,” Abbott said. “We’re simply asking the telecommunications providers to continue to keep information that they currently do.”

The data includes phone numbers and who owns the phones that make and receive the calls, but not the content of the calls, and the addresses of websites visited but not what was looked at on the site (for example, it would be known that you visited The Conversation and for how long but not what articles you read there).

In fact, the data is potentially very extensive - as a log prepared by a Guardian Australia journalist shows.

The precise detail of the government proposal is still being worked out. “What has been decided is an in-principle decision,” Brandis said. The extent to which social media would be included was being discussed. The situation of Skype is unclear.

The go-to image for intelligence agency officials, Abbott and Brandis is the comparison with the letter and envelope. “The metadata is the material on the front of the envelope and the contents of the letter will remain private,” Abbott said.

“We want to maintain the sharp distinction between metadata and content,” Brandis said.

But inevitably the edges will be fuzzy and that will increase the criticism of the proposal. As is the line between uses. Abbott said the data was “absolutely critical not just in the fight against terrorism, but in crime fighting more generally”.

The government’s position in the debate is weakened because it has released its proposal before it has finalised it. Was there such a need for rush? Perhaps it would have been better to wait until there had been full consultation with the telcos.

The government hopes to get Labor support to pass legislation on metadata (which will come after that for its other anti-terrorism initiatives). If it can, this would deal the crossbench out. But the ALP won’t commit itself until more information is available.

Bill Shorten said on Wednesday: “We believe that security of Australians is a first order issue, full stop. But we also have concerns that when you store so much information about so many Australians that this needs to be done very carefully and in a very considered way. We are concerned that the Government is going to ask the internet providers to pay for these measures which will see a new internet tax on all Australians. We are also concerned to be very careful that there is no risk that ordinary Australians are being treated as if they are criminals.”

Meanwhile, there is some crossbench scepticism and, in the case of the the Greens and the libertarian Liberal Democrat David Leyonhjelm, straight out opposition.

He recently sat in on a Senate committee hearing about the telecommunications interception act where internet service providers gave evidence. “They pointed out that metadata frequently includes content. In tweets, absolutely; emails will include the heading. So it’s not just content-free. It’s highly intrusive.

"ISPs are going to have to establish data bases to store [the material]. They have no expertise for keeping data secure,” he says. “It’s a honey pot for anyone who wants to go snooping.”

Independent senator Nick Xenophon attacks from another angle. “I am sceptical that it will be effective,” he says.

A US government advisory panel, reporting early this year, said: “We are aware of no instance in which the program [collecting phone metadata and run by the National Security Agency] directly contributed to the discovery of a previously unknown terrorist plot or the disruption of a terrorist attack. And we believe that in only one instance over the past seven years has the program arguably contributed to the identification of an unknown terrorism suspect.”

Retaining the metadata “could be a mega waste of resources”, Xenophon thinks.

Clive Palmer, whose PUPs would hold sway if Labor could not be brought onside, hasn’t yet looked at the proposals in the anti- terrorism package. But in general he regards them as a “diversion from the main economic issues. The government is trying to win popularity back with jingoism”.